The Adafruit FONA MiniGSM is an all-in-one mobile phone (cellular) module that enables you to add voice, text, SMS and data to your project. Measuring just 4.45 x 3.18 mm (1.75"x1.25") it packs a surprising amount of technology into such a small module. It features the latest SIM800 GSM cellular module.
Available with a choice of two connectors:

Adafruit 1963 - Mobile Communication Module with SMA connector (RS 124-5475)
Adafruit 1946 - Mobile Communication Module with uFL connector (RS 124-5474)

- Quad-band 850/900/1800/1900MHz
- Send and receive SMS messages
- Send and receive GPRS data (TCP/IP, HTTP)
- Make and receive voice calls using a headset via the oboard headphone socket or an external 8 Ω speaker and electret microphone.
- Scan and receive FM radio broadcasts
- PWM/Buzzer vibrational motor control (motor not included)
- AT command interface with "auto baud" detection
- Onboard LiPo battery charging circuitry enables you to recharge over micro-USB. LiPo or Li-ion battery with at least 500 mAh is recommended but not included. Two indicator LEDs show charge status.
- Level shifting circuitry so you can run it with 2.8 V to 5 V logic.
- SMA or uFL connection for external antenna (depending on version)
- Indicator LEDs for power and network connectivity
- Standard SIM card slides into the socket on the back

SIM Card
LiPo Battery – 500 mAh or larger (RS 791-6460)
Micro USB cable for battery charging (RS 121-3251)
External Antenna - SMA (RS 793-4376), uFL (704-3417)
TRRS 4-Pole Headset - Any 'iPhone' or 'Android' compatible (but not iPhone original) or external electret mic and 8 Ω speaker
Vibrating motor

This module requires a microcontroller to drive it. An Arduino board is recommended but any 3 to 5 V microcontroller with a UART can send and receive commands over the RX/TX pins.

Mobile Communication (Cellular) Modules - Adafruit